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<?php function getTree($treeByParent, $treeByCat, $id, $lastId) { $gTree = []; if ($id != $lastId) { $gTree[] = $id; if ( isset($treeByCat[ $id ]) && count($treeByCat[ $id ]) > 0 ) $gTree = array_merge( getTree($treeByParent, $treeByCat, $treeByCat[ $id ], $id), $gTree); if ( isset($treeByParent[ $id ]) && count($treeByParent[ $id ]) > 0 ) { foreach ($treeByParent[ $id ] as $cat) { $gTree = array_merge( getTree($treeByParent, $treeByCat, $cat, $id), $gTree); } } return $gTree; } } function display_parent_nodes($data, $id) { $tree = array( "parents" => array(), "children" => array(), "full" => array() ); $current = $data[$id]; $parent_id = $current === NULL ? "NULL" : $current; $childIds = array($id); $tree['parents'][] = $parent_id; while (isset($data[$parent_id])) { $current = $data[$parent_id]; $parent_id = $current === NULL ? "NULL" : $current; $tree['parents'][] = $parent_id; } echo implode(" > ", array_reverse($tree['parents'])); while ( count($childIds) > 0 ) { foreach($childIds as $child) { $children = array_keys($data, $child); foreach ($children as $ch) { $current = $data[$ch]; $child_id = $current === NULL ? "NULL" : $current; $tree['children'][] = $child_id; } $childIds = $children; } } echo " > ". implode(" > ", $tree['children']); } $treeByParent = array( 0 => array(1, 2), 1 => array(3, 7), 3 => array(4), 4 => array(5), 5 => array(6, 8) ); $treeByCat = array( 1 => 0, 2 => 0, 3 => 1, 7 => 1, 4 => 3, 5 => 4, 6 => 5, 8 => 5 ); print_r( display_parent_nodes($treeByCat, 4) ); //print_r( getTree($treeByParent, $treeByCat, 4, 0) );